Water Tank Experiments of Fish Behavior to Model of Set Nets

Abstract

In order to compare the performance of set nets, the water tank experiments of fish behavior to the model nets constructed by PVC plate were conducted, using bitterling Rhodeus ocellatus ocellatus as an experimental fish and a video behavior analyzer system for observation and analysis of the fish behavior. Five different types of set net as the model net were examined; “Oshiki-ami” (triangular set net), “Daibõ-ami” (spindle shaped set net ) of Etchu type, “Daibõ-ami” of Hidaka type, “Nakanuki-ami” (salmon set net ) and the trap net (yellowtail set net), in which the former four gears were used in the past.
In this study, the performance of model nets was assessed by the rate of remaining of the fish school. It was shown that the experimental results reflected the process of trial and error improvement of fishing techniques in set net fishery. The order of the performance obtained by the experiments was approximately in accordance with that of the historical development of the gears.